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92 600 SEL
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Discussion Starter #1
Hey all,
I recently changed the front upper control arms on my 97 S600, the ride seems to have improved but the car squeeks quite a bit in slow speed (sounds like bushings rubbing against the frame of the arm), any ideas?

thanks in advance.
 

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Premium Member
1998 140.070 CL500, 1966 406.121 U65
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1,463 Posts
The shells of the new upper arm might be too wide, so that the bolt
does not connect shell and rubber. I had to reuse the shells from my
old arms, on my new arms, as the new bolt could not press enough
to hold the rubber in place.

Also, the upper arms is to be tightened in the non-neutral position.
I do not remember if it was lower than neutral or higher. Any?

br,
syljua


br,
syljua
 

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92 600 SEL
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Discussion Starter #3
Thanks syljua but I'm not sure I underestood your comment. The shell and bolt were identical to the old one (at least as far as I could see) and didn't see any slack as you are suggesting between the bolt and the shell.
 

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Premium Member
1998 140.070 CL500, 1966 406.121 U65
Joined
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1,463 Posts
In addition to keeping the wheel spindle in the upright position,
the upper arm is a torsional bushing.

Have a look at the images here;
http://www.benzworld.org/forums/w140-s-class/1506378-control-arm-suspect-sound-i-have.html

The ends of the shell, black part, should be pressing against the ends of the rubber
that sits inside the arm, so that when rotating the arm in the shell, the action
will be hindered by the torsional force of twisting the rubber.

Some shells, in my case from Karlyn, was so far from being in contact with the
rubber, that I tried to put some shims between the edge of rubber and the inside
end of the shell. Even then, the bolt could not be tighten enough to press both
ends of the shell together, to fix the rubber to the shell end. The new bolt
was also clearly of a lower quality than the old old one, so I did not
even dare to tighten it as much I could in fear of destroying the threads.

I also tried to pre-press the shell somewhat tighter with a hydraulic press,
but that created too much distortion on the backplate of the shell for it
to be correctly fastened to the car afterwards.

My solution was to reuse the old, and more "snug" fitting shell ( since, apart
from rust, its not a part of the suspension wear) to the new rubber.

When mounted on the car, Mercedes prescribes a set position for the
"neutral" position of the rubber in the shell. That position, I believe, is not
at the normal ride height, but either slightly lower or higher. The position
is ~3cm? higher from horizontal at the outer part of the arm. I do
not know if this is higher or lower than normal ride height. Anybody know?

Edit: The top outer part of the arm should be 6.3cm higher that the top of the shell.

I think, this is to create a suspension, that is not that sensitive to small up and
down forces around the normal ride height position. Preloading the arm will help that.

qha000, if you suspect the rubber to squeak against the shell, it should
be easy enough to have a partner to bump the car up and down while looking
at, and perhaps touching, the arm? You should also look for the posibility
that the rubber squeaks against the arm * loose in the arm *.

br,
syljua
 

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92 600 SEL
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Discussion Starter #5
Great info, thanks a bunch. I'll do some peeking this weekend to see what I find.

Regards,
 
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